According to the U.S. Centers for Disease Control and Prevention, Lyme disease, which is spread by deer ticks (also known as black-legged ticks) is the most commonly reported and fastest growing vector-borne disease in the United States. About 300,000 people are affected each year, according to the CDC.

Wisconsin lies within the disease’s primary range. Ninety-five percent of the cases reported in 2012 were in New England, the mid-Atlantic states, Minnesota and Wisconsin, the CDC reported.

Since 1990, Wisconsin has identified 28,446 confirmed, probable and estimated cases. The state saw steady growth in the number of cases from 1990 to 2011, when 3,609 confirmed and probable cases were reported. There was a drop in 2012, the most recent year for which data are available.

The increased presence of deer ticks in Wisconsin and the growing number of ticks that are infected with Borrelia (Lyme disease) have made Wisconsin’s great outdoors a more dangerous place than it was a decade ago, according to UW-Madison professor of entomology Susan Paskewitz. The tick’s range also is expanding — both northward and southward, she says. The arachnids are now found in eastern and heavily populated southeastern Wisconsin, where people didn’t have to worry about them in the past.

Not only is the number of ticks carrying Lyme disease on the rise, but also the number of diseases carried by the ticks is greater than previously believed.

One glimmer of encouraging news is that the unusually harsh winter of 2013–14 appears to have diminished — or at least delayed — the onslaught of deer ticks in the state. During a recent field trip to state forests in the northern part of the state, Paskewitz found 60 to 90 percent fewer of the critters at the nymph stage than she found at this time last year. The ticks are most infectious at the nymph, or pre-adult, stage of development, because they are so tiny that they can easily evade detection — not much larger than the tip of a pen.

Difficult to diagnose

Most tick bites do not result in the transmission of Borrelia, the bacteria that causes Lyme. Those that do tend to leave the defining mark of a bull’s-eye rash, which typically appears 3-30 days after the tick bite. Other symptoms include rash, fever, headache, chills, muscle pain and joint pain.

Some people who are infected never become sick, and others exhibit no signs of the disease until it has progressed to later stages, making diagnosis difficult. Early diagnosis and treatment are critical, because untreated Lyme disease can evolve into a debilitating chronic condition that lasts for years.

Even when treated, Lyme disease can cause fatigue, body aches, migraines and fevers long after the initial course of antibiotics is finished.

Many doctors remain unaware of chronic Lyme, which is named after the Connecticut city where it was first identified. Activists have battled with doctors and insurance companies in recent years to recognize chronic Lyme disease and to prescribe and pay for the prolonged treatment it requires.

A two-day protest by victims of chronic Lyme disease and people who were misdiagnosed was staged May 22–23 at the Infectious Diseases Society of America headquarters in Arlington, Virginia.

Victims of the disease include 1980s pop star Debbie Gibson, who headlined FruitFest in Madison this year. She had to cancel her appearance at last year’s FruitFest, and she later revealed via blog and to reporters that she was suffering from Lyme disease.

Gibson’s grim experience mirrors that of many people who are infected.

At first, she had a hard time obtaining an accurate diagnosis — an all-too-common problem among Lyme sufferers. The symptoms are similar to those of many other infections. So unless the patient lives in a heavily affected area, Lyme is not usually one of the first possibilities that doctors consider.

Gibson, who thought she had mononucleosis, said that Lyme was the last thing her doctor suspected. Her condition continued to worsen until she suffered from numbness and tingling in her hands and feet — a problem she described to People magazine as “very disconcerting for a pianist and dancer, to say the least.”

Eventually, she told People, she developed night sweats, fever, nerve tremors, nightmares and migraines. She experienced dramatic weight loss that prompted rude remarks and speculation online that she was anorexic. Before she began treatment, Gibson’s cognitive thinking was so impaired that she lost her sense of direction.

Gibson finally found what she called a “Lyme-literate doctor,” who put her on an intense round of antibiotics and other medications. It was then that her slow recovery finally began.

Multiple infections

Another complication of diagnosing Lyme disease is that deer ticks can carry a host of other infections that have similar symptoms, and patients can be infected with more than one pathogen from a single bite. At least 14 infections are carried by various species of ticks. The most common ones in Wisconsin are:

• Human anaplasmosis. There are about 500 new cases of this tick-borne disease in Wisconsin each year, Paskewitz says. Symptoms include a sudden onset of high fever (102 degrees or more), chills, severe headache and muscle aches. The symptoms appear 1-3 weeks after an infectious tick bite. Although people of all ages can get anaplasmosis, it is most severe in the elderly. If left untreated with a suitable antibiotic, it can result in organ failure and death. An infected tick must be attached at least 12-24 hours to transmit the human anaplasmosis bacteria.

• Babesiosis. Symptoms include high fever, muscle aches, fatigue, headache and loss of appetite. Symptoms usually appear 1-6 weeks after a deer tick bite, but may take longer in some individuals. Most people infected with the parasite will have mild symptoms or no symptoms at all. However, people who are immune compromised may develop a severe, possibly fatal, illness.

• Ehrlichiosis. Symptoms, ranging from mild body aches to severe fever and vomiting, usually appear within a week or two after the bite of an infected tick. If treated quickly with appropriate antibiotics, ehrlichiosis generally improves within a few days. If not, it can result in life-threatening damage to the central nervous system. The disease did not appear in Wisconsin until 2011.

In addition to worrying about deer ticks, humans need to know that other species of disease-carrying ticks are expanding their range in the direction of Wisconsin. For instance, most of the Lyme disease found in Wisconsin currently is carried by the deer tick, classified by entomologists as Ixodes scapularis. But ticks of the Ixodes affinis genus, which also carry Lyme, have moved from the southeastern United States into states as far away as Wisconsin and New York.

Lone Star ticks, originally confined to the Southeast, have increased their range as far north as northeastern Missouri. The Lone Star tick carries the deadly Heartland virus, which cannot be treated with antibiotics.

The Wisconsin Department of Health Service strongly urges people to seek medical attention right away if they develop signs or symptoms of any tick-related illnesses after spending time in areas where ticks are found. Early diagnosis and treatment are vital to preventing severe illness.

“There are over 300,000 cases of Lyme each year and only 10 percent are picked up,” Dr. Robert Bransfield, clinical professor at the Robert Wood Johnson Medical school, told ABC News. “As a result, many people go on to late-stage symptoms that could have otherwise been avoided.”

PROTECT YOURSELF

While there is a vaccine to protect family pets against Lyme disease, there’s no approved vaccination for humans. The only protection for people is to avoid disease-bearing ticks.

Experts recommend that people spending time outdoors check themselves for ticks periodically and remove them immediately. It takes 24 to 48 hours for the tick to transmit the bacteria that causes Lyme disease. The following precautions are advised for people spending time outdoors in the summer:

• Know when you’re in tick habitat — brushy, wooded areas — where you will need to take precautions.

• Use a good tick repellent, such as a product containing permethrin or DEET, and follow the manufacturer’s instructions.

• Wear clothes that will help to shield you from ticks. Long-sleeved shirts and long pants are best. Tuck your pants into the top of your socks or boots to create a “tick barrier.”

• Check frequently for ticks and remove them promptly. This is an important step in preventing disease.

• Remove the tick slowly and gently using a pair of tweezers. Folk remedies like Vaseline, nail polish remover or matches are not safe or effective methods of tick removal.